Sterilizable pump and systems for use with sterile fluids

ABSTRACT

An improvement for a control system for a surgical procedure is provided. The control system includes an electrosurgical instrument connectable to a source of electrosurgical energy, and a pump for circulating fluid to the electrosurgical instrument. The improvement includes a pump housing configured and adapted for selective connection in an opening provided in the source of electrosurgical energy. The housing defines a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/608,037, filed on Sep. 8, 2004, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to sterilizable pumps and systems, and more particularly to sterilizable pumps and systems, typically used to circulate sterile fluids and the like, to a target surgical site and/or through a surgical instrument.

2. Background of Related Art

A wide variety of pump types have been used in the past for pumping any number of a variety of different liquids for any of a number of different functions and applications. Typically a peristaltic-type pump is used in connection with many medical applications and is applied externally of the fluid delivery tube. Thus, the peristaltic pump does not interfere with the sterile state which must be maintained for the infusion fluid within the fluid delivery tube.

Many peristaltic pumps are typically used in medical, biomedical and laboratory applications, including and not limited to, irrigation devices and/or systems, suction devices and/or systems, circulation devices and/or systems, and the like. One example of a peristaltic pump is shown schematically in FIG. 1 and is described in commonly assigned U.S. Pat. No. 6,575,969, the entire contents of which are incorporated herein by reference. This so-called “cool-tip” radiofrequency thermosurgery electrode system includes an example of a pump for circulating cooling fluid.

More particularly and as seen in FIG. 1, an insulated electrode shaft 104 with exposed tip 103 is provided for insertion into a patient's body so that tip 103 achieves a target volume to be ablated. A high frequency generator such as a radiofrequency generator 107 is provided for supplying RF power to electrode shaft 104, as shown by the RF power P line. At the same time, electrode shaft 104, is provided with a temperature sensor, provides feed back to the RF generator or controller circuit 109 relating to a temperature reading To or multiple temperature readings of a similar nature of the tissue coolant fluid or tip arrangement. Depending upon the temperature reading, the RF output power P may be modified by controller 109 by modulating the RF voltage, current, and/or power level, accordingly, to stabilize the ablation volume or process. If temperature rises to boiling, as indicated by temperature measurement To, the power could be either shut off or severely cut back by generator 107 or controller 109. Thus a feedback loop between power and temperature or any other set of parameters associated with the lesion process can be implemented to make the process safer or to simply monitor the process altogether.

As further seen in FIG. 1, element 108 represents the coolant fluid supply and pump system which can be configured to measure pressure and/or flow. Input flow from element 108 to electrode shaft 104 and output flow are indicated by the arrows to and from the electrode shaft 104 and element 108, respectively. Accordingly, the controller 109 monitors the procedure and regulates the fluid flow of the coolant between controller 109 and element 108 which, in turn, prevents the electrode from over heating. In conjugation, the combined mediation of flow, power, temperature, or other lesioning parameters could be integrated in controller 109, and the entire system of generator 107, element 108, and controller 109 can be one large feedback control network and system. Fluid bath 110 may also be included with the system as a reservoir of coolant fluid which may also be regulated by controller 109.

Typically, element 108, including the pump, is an integral part of control system 100. Accordingly, should the pump fail, break down, become contaminated or the like, the entire control system 100 needs to be replaced or extensive work performed on control system 100 in order to replace, remove, sterilize, dispose and/or otherwise treat the pump of element 108.

Despite the importance of pump systems in medical, biomedical and laboratory applications, as described above, the use of pump systems in these and many other applications has met with some drawbacks.

For example, typical rotary peristaltic-type pumps function on rotary action principles, wherein the fluid delivery tube is wrapped around a shaft and is periodically squeezed and/or pinched at varying locations along the length thereof (e.g., by means of rollers that are made to rotate about a central shaft) thus propelling the fluid through the tube.

An issue which may arise with rotary peristaltic-type pumps is that the fluid delivery tube must recover its cylindrical shape following the passage of each roller thereover (i.e., the fluid squeezes) which may effect the tube's elasticity and impede the tube's ability to restore to its normal shape which may unnecessarily limit the operation of the pump.

Another issue which may arise with rotary peristaltic-type pumps is that the repetitive squeezing and/or pinching of the fluid delivery tube tends to weaken the tubing which, in turn, may lead to eventual leaking during normal usage.

Accordingly, a need exists for improved pumps and/or systems for use with sterile fluids which overcome at least some of the deficiencies and/or drawbacks of existing pumps and/or systems.

A need exists for improved pumps and/or pump systems which can be or are sterilized and which are used in connection with the transmission of sterile fluids.

A need also exists for improved pumps and/or pump systems which can be selectively coupled and un-coupled to and from a driving mechanism of a control system as needed and/or desired.

A need exists for improved pumps and/or pump systems having interchangeable components, which components may be each individually sterilizable, replaceable and/or disposable.

A need exists for improved pumps and/or pump systems for use with cool-tip radiofrequency thermosurgery electrode system.

SUMMARY

Sterilizable pumps and systems, typically used to circulate sterile fluids and the like, to a target surgical site and/or through a surgical instrument, are provided.

According to an aspect of the present disclosure, a pump for selective fluid connection with a control system for circulating fluid to a target surgical site is provided. The pump includes a housing defining a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber.

The pump further includes an impeller assembly rotatably supported in the circular chamber of the housing. The impeller assembly includes a shaft operatively supported within the bore of the housing; an impeller having an inner ring operatively connect to the shaft, such that rotation of the shaft results in rotation of the impeller, an outer ring configured and dimensioned for sliding engagement with an inner annular surface of the cylindrical chamber of the housing, and a plurality of radially angled vanes extending between the inner ring and the outer ring, wherein the vanes define a plurality of chambers around the inner ring. Accordingly, when the impeller assembly is positioned within the circular chamber of the housing a portion of the chambers of the impeller, in proximity to the inlet, are un-compressed and a portion of the chambers of the impeller in proximity to the outlet, are compressed.

According to another aspect of the present disclosure, an improvement for a control system for a surgical procedure is provided. The control system includes an electrosurgical instrument connectable to a source of electrosurgical energy, and a pump for circulating fluid to the electrosurgical instrument. The improvement includes a pump housing configured and adapted for selective connection in an opening provided in the source of electrosurgical energy. The housing defines a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber.

The improvement further includes an impeller assembly rotatably supported in the circular chamber of the housing. The impeller assembly includes a shaft operatively supported within the bore of the housing; an impeller having an inner ring operatively connect to the shaft, such that rotation of the shaft results in rotation of the impeller, an outer ring configured and dimensioned for sliding engagement with an inner annular surface of the cylindrical chamber of the housing, and a plurality of radially angled vanes extending between the inner ring and the outer ring, wherein the vanes define a plurality of chambers around the inner ring. Accordingly, when the impeller assembly is positioned within the circular chamber of the housing a portion of the chambers of the impeller, in proximity to the inlet, are un-compressed and a portion of the chambers of the impeller in proximity to the outlet, are compressed.

It is envisioned that at least the vanes of the impeller are formed from a material selected from the group consisting of elastomeric polymers, plastic polymers, and blends of said elastomeric and plastic polymers.

The housing may further define a first annular groove formed in a surface of the cylindrical chamber, which first annular groove is in fluid communication with the cylindrical chamber and the inlet; and a second annular groove formed in a surface of the cylindrical chamber, which second annular groove is in fluid communication with the cylindrical chamber and the outlet.

The pump may further include a cover selectively securable to the housing for retaining the impeller assembly within the cylindrical chamber. Accordingly, a first end of the shaft of the impeller assembly may project from one side of the housing and a second end of the shaft of the impeller assembly may be supported by the cover.

The pump may further include a sealing member provided around the periphery of the cylindrical chamber.

In operation, rotation of the impeller assembly results in compression of the chambers of the impeller in the vicinity of the outlet to force fluid out of the pump, and expansion of the chambers of the impeller in the vicinity of the inlet to draw fluid into the pump.

The housing may be configured and adapted for selective insertion into a complementary opening provided in the control system.

The pump may further include a gear supported on the first end of the shaft of the impeller assembly.

It is envisioned that complementary mating elements may be provided on the housing of the pump and in the opening of the source of electrosurgical energy for securing the pump within the opening of the source of the electrosurgical energy.

The presently disclosed sterilizable pumps and systems, together with attendant advantages, will be best understood by reference to the following detailed description in conjunction with the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure.

FIG. 1 is a schematic diagram of a prior art cool-tip control system for RF heating ablation showing an RF generator, coolant system, fluid bath source, and control system which monitors and regulates critical parameters relating to temperature, power and fluid flow;

FIG. 2 is a perspective view of a pump according to the present disclosure;

FIG. 3 is a front elevational view of the pump of FIG. 2 shown in operative engagement with a motor;

FIG. 4 is an exploded perspective view of the pump and pump housing of FIGS. 2 and 3;

FIG. 5 is a front elevational view of the internal configuration of the pump housing of FIGS. 2-4; and

FIG. 6 is a perspective view of an exemplary control system including an opening for receiving the pump of FIGS. 2-5 therein.

DETAILED DESCRIPTION

Referring again to FIG. 1, a prior art control system for RF heating ablation is shown generally as 100. Control system 100 includes an insulated electrode shaft 104 having an exposed tip 103 for insertion into a patient's body such that exposed tip 103 can achieve a target volume to be ablated. Electrode shaft 104 preferably extends from a hub 106 including connection means (not shown) for connecting electrode shaft 104 to RF generator 107 and coolant supply and pump 108.

Preferably, RF generator 107 supplies RF power to electrode shaft 104, as shown by the RF power connection “P”. At the same time, electrode shaft 104 which includes a temperature sensor (not shown), feeds temperature information back to RF generator 107 and/or a controller circuit 109 relating to a temperature reading To or multiple temperature readings of the tissue coolant fluid or tip arrangement. According to the temperature reading, any modulation of the RF output power “P” is accorded by controller 109. More particularly, controller 109 modulates the RF voltage, current, and/or power level to stabilize the ablation volume or process. If temperature reading To rises to a boiling point, the power is either shut off or severely cut back to generator 107 by controller 109. Thus a feedback loop between power and temperature or any other set of parameters associated with the lesion process can be implemented to monitor the overall process.

In addition, as seen in FIG. 1, control system 100 further includes power measurement connections from RF generator 107 to controller 109 and a feedback power control signal from controller 109 to RF generator 107. The entire heating process may be preconfigured by the operator before the procedure based on the imaging and preplanned calculations of ablation volume verses the tip geometry and other ablation parameters. Thus, controller 109 is capable of regulating the entire heating process by controlling the RF power “P” from generator 107.

With continued reference to FIG. 1, control system 100 further includes a coolant fluid supply and pump system 108 with potential thermo-monitoring, pressure monitoring, flow monitoring, etc. Input flow from coolant fluid supply and pump system 108 to electrode shaft 104 and output flow from the electrode shaft are indicated by the arrows which connect hub 106 and the coolant fluid supply and pump system 108. Such input and output flow can be monitored by appropriate pressure or flow monitoring elements or detection devices (not shown). These are well known in the fluid control industry. Accordingly, the fluid flow and the temperature of the coolant can be fed back between controller 109 and coolant supply 108 so the controller 109 can regulate the input and output flow. Combined regulation mediation of flow, power, temperature, and/or other lesioning parameters may also be integrated in controller 109, the generator 107, and the coolant supply 108. The controller 109 may also be configured as one large feedback control network and system.

It is further envisioned that control system 100 can include a reservoir of coolant fluid 110 which may have possible interior temperature regulation within the fluid bath. Bath temperatures and control signals are fed back and forth to controller system 109. These parameters also could be integrated in the overall control of the ablation process. Indwelling controllers, electronics, microprocessors, or software may be included to govern the entire process or allow preplanned parameters to be configured by the operator based on the selection of a tip geometry and overall ablation volume which are typically selected according to a tumor or pathological volume to be destroyed. Many variants or interconnections of the block diagram shown in FIG. 1 or additions of the diagram could be devised by those skilled in the art of fluid control power and regulation systems.

Turning now to FIGS. 2-4, a sterilizable pump in accordance with one embodiment of the present disclosure, for use in control system 100 and with coolant supply 108, is shown generally as 200. Pump 200 includes a body or housing 202 defining a chamber 204 (preferably circular) therein. Housing 202 further includes an aperture or inlet 206 (shown in hidden lines in FIG. 5) and a discharge or outlet 208 (shown in hidden lines in FIGS. 2 and 5) formed therein. Housing 202 further includes a bore 210 formed therein for rotatably receiving and/or supporting a shaft 230, as will be discussed in greater detail below. Preferably, shaft 230 is cylindrical. Bore 210 is sized to receive shaft 230 and an annular bearing collar (not shown) therein. Bore 210 defines the axis of rotation of shaft 230.

With reference to FIGS. 4 and 5, inlet 206 leads to and is in fluid communication with a first arcuate groove 224 that extends substantially circumferentially through an angle of less than about 180°. Similarly, outlet 208 is in fluid communication with a second arcuate groove 226 that extends substantially circumferentially through an angle of less than about 180°. Preferably, first and second grooves 224 and 226 are independent and isolated from one another. First and second grooves 224 and 226 are formed in the same wall of housing 202. In particular, first arcuate groove 224 is disposed below second arcuate groove 226.

As best seen in FIG. 5, bore 210 includes a central axis “X₁” (i.e., the axis of rotation of shaft 230) which is slightly offset from a central axis “X₂” of chamber 204 thereby providing a degree of eccentricity “E” between bore 210 and chamber 204. As will be described in greater detail below, it is eccentricity “E” which creates the pumping effect of pump 200. Preferably, central axis “X₂” is offset from central axis “X₁” in the direction of second arcuate groove 226.

As best seen in FIG. 4, pump 200 further includes an impeller assembly generally designated as 228. Impeller assembly 228 includes a shaft 230 to which is operatively connected an impeller 232. Impeller 232 includes a substantially rigid inner ring 234, having an inner bore (not shown) allowing inner ring 234 to be secured to shaft 230, and a substantially rigid outer ring 236.

Impeller 232 further includes a plurality of flexible, resilient, elastomeric webs, spokes or vanes 238 extending between an inner tubular hub portion 240 and an outer rim portion 242. Preferably, vanes 238 maintain inner ring 234 substantially concentric with outer ring 236. Desirably, vanes 238 extend from hub portion 240 in a substantially arcuate fashion and attach to outer rim portion 242. Vanes 238 define a plurality of chambers 244 between hub portion 240 and rim portion 242. Desirably, inner tubular hub portion 240 is secured to an outer surface of inner ring 234 and outer rim portion 242 is secured to an inner surface of outer ring 236.

Vanes 238 are preferably molded or fabricated in a single piece from suitable material exhibiting good flexure, fatigue and mechanical properties, such as elastomers (e.g., Neoprene, Nitrile, fluouroelastomer, etc.), plastic (e.g., Teflon, Nylon, etc.), compounds of plastic and elastomers (e.g., Santoprene), or other fabrics (e.g., Kevlar). If molded from Neoprene, it is desirable that vanes 238 have a Shore A hardness range from about 55 to about 85.

Pump 200 further includes a cover 250 for closing off chamber 204 and retaining impeller assembly 228 therein. Preferably, cover 250 creates a seal around chamber 204 to thereby prevent and/or inhibit the escape of fluids and/or pressure therefrom. As seen in FIG. 4, it is envisioned that cover 250 is secured to housing 202 by screws or bolts 252, however, it is contemplated and within the scope of the present disclosure for cover 250 to be otherwise secured to housing 202 by clamps, adhesives, pins ultrasonic welding and the like. Preferably, a sealing member 254, in the form of a bead of sealing material or a gasket, may be provided around chamber 204 to further prevent and/or inhibit the escape of fluid or pressure therefrom. Cover 250 is preferably formed to support an end 230 b of shaft 230, such as, by a recess or the like (not shown) formed therein. Providing pump 200 with a cover 250 enables pump 200 to be opened after use and for the various components of pump 200, e.g., shaft 230, impeller assembly 228, etc., to be cleaned, sterilized and/or replaced as needed.

As seen in FIGS. 2-4, pump 200 can further include a gear or sprocket 260 supported on or otherwise operatively coupled to a portion 230 a of shaft 230 extending out of housing 202. Preferably, shaft 230 and gear 260 are keyed such that rotation of gear 260 transfers a corresponding rotation to shaft 230 and subsequently to impeller assembly 228. Accordingly, as seen in FIG. 3, gear 260 of pump 200 can be operatively coupled to a gear 272 of a motor or other drive mechanism 270. Alternatively, it is envisioned that shaft 230 of pump 200 can be directly coupled and/or otherwise connected to motor 270.

In assembling pump 200, impeller assembly 228 is positioned in chamber 204 such that when shaft 230 is inserted through bore 210 formed in housing 212, the eccentricity “E” between chamber 204 in housing 202 and bore 210 at least partially compresses vanes 238 in a radial segment thereof (i.e., closing, squeezing and/or pinching chambers 244 in that radial segment). Meanwhile, vanes 238 in another radial segment thereof are substantially un-compressed (i.e., chambers 244 in the other radial segment are maintained substantially open). With impeller assembly 228 so positioned, cover 250 can be attached to housing 202 to thereby close and/or seal chamber 204.

In use, due to the eccentricity between chamber 204 and bore 210, as impeller assembly 228 is rotated about shaft 230, chambers 244 of impeller assembly 228 oscillate between at least partially compressed conditions and substantially expanded conditions. This is due to the fact that as impeller assembly 228 rotates, outer ring 236 and/or outer rim portion 242 of impeller assembly 228 rides against an inner annular wall 204 a (see FIGS. 4 and 5) of chamber 204 of housing 202 while inner hub 240 is driven by shaft 230. The eccentricity of shaft 230 relative to chamber 204 of housing 202 distorts and/or compresses chambers 244, thereby creating a rotary peristaltic effect.

In operation, as shaft 230 is rotated to rotate impeller assembly 228, fluid (e.g., cooling fluid, water, saline, etc.) enters and/or is otherwise drawn into impeller 232 from inlet 206 and first annular groove 224 to fill the un-compressed chambers 244 in proximity therewith. The fluid is drawn into chambers 244 located proximate inlet 206 and first annular groove 224 due to the localized expansion of chambers 244, during rotation of impeller assembly 228, thereby creating a partial vacuum to draw the fluid therein. As impeller assembly 228 is rotated, the fluid is carried by un-compressed chambers 224 of impeller 232 from first annular groove 224 to second annular groove 226 and from inlet 206 to outlet 208. As the un-compressed chambers 244, carrying the fluid, are brought into close proximity to second annular groove 226, eccentricity “E” causes the un-compressed chambers 244 to compress against inner wall 204 a of chamber 204 and thereby squeeze out or expel the fluid carried therein into second annular groove 226 and out through outlet 208. Once again, as the compressed chambers 244 are brought into close proximity to first annular groove 224 the compressed chambers 244 begin to uncompress or expand, thereby creating a partial vacuum, to thereby draw additional fluid into chambers 244. The process is repeated for every revolution of impeller assembly 228.

Preferably, as described above, motor 270, including gear 272, can be operatively connected to gear 260 of pump 200 to drive and/or spin shaft 230 and in turn impeller assembly 228. Accordingly, it is envisioned that the faster motor 270 is driven, the faster impeller assembly 228 is driven, and, in turn, the faster the rate of fluid flow through pump 200.

It is envisioned that inlet 206 and outlet 208 can each include a valve, a fluid coupling and/or the like (not shown). In this manner, pump 200 can be simply coupled to the output tubing of a source of fluid and to the input tubing of an output source. For example, pump 200 can be fluidly coupled to the input flow line between coolant supply 108 and electrode shaft 104 of control system 100 (see FIG. 1). In this manner, pump 200 provides electrode shaft 104 with a substantially uniform rate of fluid flow therethrough, thereby maintaining a substantially constant temperature during the surgical procedure.

Following use of control system 100, pump 200 can be unconnected and/or uncoupled from the input and/or output tubing and pump 200 can be: disposed of; sterilized in its entirety; disassembled for sterilization of the individual components thereof; disassembled for replacement of the individual components thereof; cleaned; and the like. In this manner, pump 200 can be reused for other surgical procedures. Pump 200 may also be disposable or partially reposable. Moreover, the tendency for the inlet and outlet tubing to crack due to the fatigue which may occur during the use of a peristaltic pump is eliminated.

As seen in FIG. 6, it is envisioned that pump 200 may be in the form of a cartridge which may be selectively removably inserted into a slot or opening 120 provided in the housing of or otherwise connected to control system 100 or RF generator 107. In particular, housing 202 of pump 200 has a particular shape and is selectively insertable into a complementary slot or opening 120 of control system 100 or RF generator 107. Pump 200, and either control system 100 or RF generator 107 may include complementary mating elements 280 and 180, respectively, which permit secure engagement between pump 200 and either control system 100 or RF generator 107. Upon connection of pump 200 to either control system 100 or RF generator 107, gear 260 of pump 200 engages gear 272 of motor 270 (not shown in FIG. 6).

While a peristaltic pump has been shown and described, it is understood that other types of pumps can be used herein without departing from the scope of the invention.

Although the illustrative embodiments of the present disclosure have been described herein, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the disclosure. All such changes and modifications are intended to be included within the scope of the present disclosure. 

1. A pump for selective fluid connection with a control system for circulating fluid to a target surgical site, the pump comprising: a housing defining: a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber; and an impeller assembly rotatably supported in the circular chamber of the housing, the impeller assembly including: a shaft operatively supported within the bore of the housing; an impeller having an inner ring operatively connect to the shaft, such that rotation of the shaft results in rotation of the impeller, an outer ring configured and dimensioned for sliding engagement with an inner annular surface of the cylindrical chamber of the housing, and a plurality of radially angled vanes extending between the inner ring and the outer ring, wherein the vanes define a plurality of chambers around the inner ring; wherein when the impeller assembly is positioned within the circular chamber of the housing a portion of the chambers of the impeller, in proximity to the inlet, are un-compressed and a portion of the chambers of the impeller in proximity to the outlet, are compressed.
 2. The pump according to claim 1, wherein at least the vanes of the impeller are formed from a material selected from the group consisting of elastomeric polymers, plastic polymers, and blends of said elastomeric and plastic polymers.
 3. The pump according to claim 2, wherein the housing further defines: a first annular groove formed in a surface of the cylindrical chamber, which first annular groove is in fluid communication with the cylindrical chamber and the inlet; and a second annular groove formed in a surface of the cylindrical chamber, which second annular groove is in fluid communication with the cylindrical chamber and the outlet.
 4. The pump according to claim 3, further comprising a cover selectively securable to the housing for retaining the impeller assembly within the cylindrical chamber, wherein a first end of the shaft of the impeller assembly projects from one side of the housing and a second end of the shaft of the impeller assembly is supported by the cover.
 5. The pump according to claim 4, further comprising a sealing member provided around the periphery of the cylindrical chamber.
 6. The pump according to claim 3, wherein rotation of the impeller assembly results in compression of the chambers of the impeller in the vicinity of the outlet to force fluid out of the pump, and expansion of the chambers of the impeller in the vicinity of the inlet to draw fluid into the pump.
 7. The pump according to claim 6, wherein the housing is configured and adapted for selective insertion into a complementary opening provided in the control system.
 8. The pump according to claim 7, further comprising a gear supported on the first end of the shaft of the impeller assembly.
 9. In a control system for a surgical procedure, wherein the control system includes an electrosurgical instrument connectable to a source of electrosurgical energy, and a pump for circulating fluid to the electrosurgical instrument, the improvement comprising: a pump housing configured and adapted for selective connection in an opening provided in the source of electrosurgical energy, the housing defining: a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber; and an impeller assembly rotatably supported in the circular chamber of the housing, the impeller assembly including: a shaft operatively supported within the bore of the housing; an impeller having an inner ring operatively connect to the shaft, such that rotation of the shaft results in rotation of the impeller, an outer ring configured and dimensioned for sliding engagement with an inner annular surface of the cylindrical chamber of the housing, and a plurality of radially angled vanes extending between the inner ring and the outer ring, wherein the vanes define a plurality of chambers around the inner ring; wherein when the impeller assembly is positioned within the circular chamber of the housing a portion of the chambers of the impeller, in proximity to the inlet, are un-compressed and a portion of the chambers of the impeller in proximity to the outlet, are compressed.
 10. The control system according to claim 9, wherein at least the vanes of the impeller are formed from a material selected from the group consisting of elastomeric polymers, plastic polymers, and blends of said elastomeric and plastic polymers.
 11. The control system according to claim 10, wherein the housing further defines: a first annular groove formed in a surface of the cylindrical chamber, which first annular groove is in fluid communication with the cylindrical chamber and the inlet; and a second annular groove formed in a surface of the cylindrical chamber, which second annular groove is in fluid communication with the cylindrical chamber and the outlet.
 12. The control system according to claim 11, further comprising a cover selectively securable to the housing for retaining the impeller assembly within the cylindrical chamber, wherein a first end of the shaft of the impeller assembly projects from one side of the housing and a second end of the shaft of the impeller assembly is supported by the cover.
 13. The control system according to claim 12, further comprising a sealing member provided around the periphery of the cylindrical chamber.
 14. The control system according to claim 11, wherein rotation of the impeller assembly results in compression of the chambers of the impeller in the vicinity of the outlet to force fluid out of the pump, and expansion of the chambers of the impeller in the vicinity of the inlet to draw fluid into the pump.
 15. The control system according to claim 14, wherein the housing is configured and adapted for selective insertion into a complementary opening provided in the control system.
 16. The control system according to claim 15, further comprising a gear supported on the first end of the shaft of the impeller assembly.
 17. The control system according to claim 16, further comprising complementary mating elements provided on the housing of the pump and in the opening of the source of electrosurgical energy for securing the pump within the opening of the source of the electrosurgical energy. 